This is the best item the Navy has for fighting class B fires. A class B fire is any flammable liquid, many fuel. Just like everything else, if you can shorten it a Sailor will. AFFF is short for Aqueous Film Forming Foam.

If you see a fire department spraying foam like material on a fire, that’s what it is. The foam will actually float on top of a fuel spill and cut off the supply of oxygen to the fire.

The following history of AFFF comes from our friends over at Wikipedia:


In the late 1800s, a method of extinguishing flammable liquid fires by blanketing them with foam was introduced. The original foam was a mixture of two powders and water produced in a foam generator. It was called chemical foam because of the chemical action to create it. Generally, the powders used were sodium bicarbonate and aluminum sulfate, with small amounts of saponin or liquorice added to stabilize the bubbles. Hand-held foam extinguishers used the same two chemicals in solution: to actuate the extinguisher, a seal was broken and the unit inverted, allowing the liquids to mix and react. Chemical foam is a stable solution of small bubbles containing carbon dioxide with lower density than oil or water, and exhibits persistence for covering flat surfaces. Because it’s lighter than the burning liquid, it flows freely over the liquid surface and extinguishes the fire by a smothering action. Chemical foam is considered obsolete today because of the many containers of powder required, even for small fires.

In the 1940s Percy Lavon Julian developed an improved type of foam called Aerofoam. Using mechanical action, a liquid protein-based concentrate, made from soy protein, was mixed with water in either a proportioner or an aerating nozzle to form air bubbles with the free flowing action. Its expansion ratio and ease of handling made it popular. Protein foam is easily contaminated by some flammable liquids, so care should be used so that the foam is only applied above the burning liquid. Protein foam has slow knockdown characteristics, but it is economical for post fire security.

In the 1960s National Foam, Inc. developed fluoroprotien foam. Its active agent is a fluorinated surfactant which provides an oil-rejecting property to prevent contamination. It is generally better than protein foam because its longer blanket life provides better safety when entry is required for rescue. Fluoroprotein foam has fast knockdown characteristics and it can also be used together with dry chemicals which destroy protein foam.

In the mid 1960s the US Navy developed aqueous film-forming foam (AFFF) . This synthetic foam has a low viscosity and spreads rapidly across the surface of most hydrocarbon fuels. A water film forms beneath the foam which cools the liquid fuel, which stops the formation of flammable vapors. This provides dramatic fire knockdown, an important factor in crash rescue fire fighting.

In the early 1970s National Foam, Inc. invented Alcohol Resistant AFFF technology. AR-AFFF is synthetic foam developed for both hydrocarbon and polar solvent materials. Polar solvents are combustible liquids that destroy conventional fire fighting foam. These solvents extract the water contained in the foam, breaking down the foam blanket. Therefore, these fuels require an alcohol or polar solvent resistant foam. Alcohol resistant foam must be bounced off of a surface and allowed to flow down and over the liquid to form its membrane, compared to standard AFFF that can be sprayed directly onto the fire. Since AR-AFFF is effective on a variety of fuels, it the most accepted for American industry.



So basically some chemist figured out a method to make water based foam float on fuel. Which is opposite from the normal fuel water relationship. As a person who has trained and used this foam, I can say this stuff is a real life saver. Although, I am glad I never had to use it while at sea.

All primary engineering spaces on ships have AFFF sprinkler systems. All flight deck surfaces and hanger bays have AFFF systems as well. The Navy could not operate without having the foam ready to put out any fire that should crop up.

Most civilian fire departments use AFFF in one form or another. Some large industrial plants also use AFFF in their fire suppression systems.